Journal article "Optimal control of polar sea-ice near its tipping points", published by Nature, November 2024.
The Earth’s climate faces a high risk of crossing tipping points and could face a rapid transition into an ice-free world if greenhouse gas (GHG) emissions continue to increase. Tipping points are critical climate thresholds which, once surpassed or 'tipped', can lead to rapid cascading changes in the climate system. Preventing the crossing of these tipping points will come at a large cost, but the price of delaying this investment into the future would likely be much higher. For some tipping points (e.g. sea ice loss), the cost to control the impacts after tipping could nearly quadruple. Now more than ever, we need to investigate the possibility of arresting or even reversing the crossing of tipping points in a timely manner to mitigate their climate security impacts.
One of the article's key findings is that tipping points have an ‘overshoot window’. This is a period after the tipping point is crossed where the cost of reversal does not surge straight away but increases linearly over time - for example, when ocean waters take longer to heat up and delay rapid changes. Whilst this could give the world some leeway before the onset of extreme changes to the climate, this is ‘no free lunch’. The larger the overshoot window for a tipping point, the higher the cost of intervention once the overshoot window ends and the tipping point is fully crossed.
The article shines a spotlight on polar-sea ice levels, which were found to be dangerously close to tipping - the impacts of which, especially once the overshoot period ends, would become exceedingly expensive to control. Additionally, not all climate tipping points are reversible (e.g. loss of flora and fauna) and reversing tipping points could take considerably more time and effort than it took to cross them.
The research community thus calls for urgent action to avert tipping points risks as current climate policies, even if implemented successfully, are unlikely to limit global warming to 2°C.
This text is based on extracts from a research article written by Parvathi Kooloth, Jian Lu, Craig Bakker, Derek DeSantis & Adam Rupe, published in npj Climate and Atmospheric Science in November 2024. The original journal article can be found here.